A wireless communication device operates in a wireless communication system to provide a user of the device with portable communications. A wireless communication device communicates with the wireless communication system or other wireless communication devices via electromagnetic signals, such as those in the radio frequency (RF) range, for example. The wireless communication device may communicate voice only, data only or both voice and data. The format of the electromagnetic signal communicated between the wireless communication device and the wireless communication system or other devices may be either analog or digital. Examples of wireless communication devices comprise radiotelephones, pagers, two-way radios, personal data assistants, and personal notebooks. The radiotelephones comprise cellular and cordless subscriber units.
Wireless communication devices use various alert techniques to indicate to a user of a wireless communication device that an incoming desired signal has been received. For example, a radiotelephone alerts the user when an incoming call signal is received, and a pager alerts the user when an incoming page signal is received. Generally, these alert techniques include audible, visual and tactile alert generators. The audible alert generator is typically implemented with an acoustic transducer, i.e. a speaker, sometimes known as a ringer. The visual alert generator is typically implemented with a display or a separate indicator. The tactile alert generator is typically implemented with an axially offset counterweight driven by a motor to cause a vibrating sensation.
Audible alert generators are generally known to be implemented in virtually all wireless communication devices. When a desired signal has been received, the wireless communication device activates the audible alert generator to produce a sound, such as a ring or beep, thereby alerting the user. A problem with audible alert generators is that the sound produced can be disturbing to others in environments where there is a low ambient noise level, and may not be heard by the user in environments where there is a high ambient noise level.
In landline telephone systems, landline telephone subscriber units have audible alert generators and can generate distinctive audible alert patterns, such as distinctive ringing or distinctive call-waiting, responsive to signals generated by the landline telephone system. Generally, distinctive ringing and distinctive call-waiting consists of sequenced, variable-length bursts of power ringing interspersed with variable length silent intervals. Distinctive ringing and distinctive call-waiting for landline telephone subscriber units is described in Bellcore's LATA Switching Systems Generic Requirements, Class .sup.SM Feature: Distinctive Ringing/Call Waiting, FSD 01-01-1110, TR-TSY-000219, Issue 2, November 1988, Revision 1, May 1992.
In a radiotelephone system, radiotelephone subscriber units have audible alert generators and can generate distinctive audible alert patterns, such as distinctive ringing, responsive to alert codes generated by the radiotelephone system. Generally, distinctive ringing in the radiotelephone system is implemented by varying the pitch and cadence or duty cycle, of the audible alert signal. Pitch represents a distinction between tones, usually based on frequency. Cadence or duty cycle is the on/off pattern of the tones. Distinctive ringing for radiotelephone subscriber units is described in EIA/TIA INTERIM STANDARD, Cellular System Dual-Mode Mobile Station-Base Station Compatibility Standard, IS-54-B, Section 2.7.3.1.3.3.1, Telecommunications Industry Association, April 92.
Visual alert generators are generally known to be implemented in most wireless communication devices. When a desired signal has been received, the wireless communication device activates the visual alert generator to produce a visual indicator, such as a flashing icon in the display or a flashing light, thereby alerting the user. A problem with visual alert generators is that the visual indicator produced can go undetected by the user for some period of time until the user actually looks at the visual indicator. Therefore, the audible alert generator is typically used as a primary alert and the visual alert generator is typically used as a secondary or redundant alert.
Tactile alert generators are generally known to be implemented in only some wireless communication devices. Tactile alert generators are typically used in wireless communication devices that are small enough to be portable and worn on the user such that the tactile sensation is felt. Some pagers, for example, have the motor driving the axially offset counter-weight to produce a vibrating sensation against the user. When a desired signal has been received, the wireless communication device activates the tactile alert generator to produce a tactile sensation, such as vibration, thereby alerting the user. A problem with tactile alert generators is that the tactile sensation produced can go undetected by the user when the wireless communication device is not worn by the user or closely coupled to the user in some manner. Another problem with tactile alert generators is that various users may not be responsive to the same tactile sensation produced by the tactile alert generator due to the physiology and clothing of the various users and the location of the wireless communication device on the user's body. Therefore, the tactile alert generator is typically used in environments where the ambient noise level is very low such that others in the area are not disturbed or where the ambient noise level very high such that the user is alerted when the audible alert cannot be heard.
Accordingly, there is a need for a wireless communication device that generates a plurality of distinctive tactile alert patterns.